A natural history study and controlled randomized clinical trial will be done to determine the effects of systemic hypertension on diabetic retinopathy. The study will test the effects of rigid control of hypertension versus routine high blood pressure management. Special attention will be paid to characterization of the renin angiotension system and sequential retinal photographs and fluorescein angiography will be used to evaluate the presence and severity of diabetic retinopathy in quantitative terms.